Farmers who apply fertilizer to their fields, particularly manure, need to be aware that if the fertilizer winds up in a waterway, they could be facing fines as farmers in northwestern Ohio did last summer.

Applying manure can be particularly tricky because it's often in liquid form and typically applied to the surface of fields, unlike most commercial fertilizers. So, if manure is spread and not fully incorporated into the soil before a heavy rainfall, the manure could run
off a farm field and into a nearby body of water.

In August 2017, three fish kills occurred in separate incidents in Williams, Allen and Hardin counties. Farmers had treated their fields with manure, then a major rainstorm came through.

Given the risks associated with spreading manure, it's important for farmers to have written plans specifying how often, when and where they're going to place manure or commercial fertilizer and to keep records on each spreading, said Peggy Hall, agricultural
and resource law field specialist for Ohio State University Extension. OSU Extension is the outreach arm of the College of Food, Agricultural, and Environmental Sciences (CFAES) at The Ohio State University.

Hall will address potential liability that farmers have when applying manure to their fields at the upcoming Conservation Tillage and Technology Conference March 6-7. She is among a slate of speakers for the event, which is sponsored in part by OSU
Extension, and will take place at Ohio Northern University in Ada.

Among the sponsors for the event are OSU Extension and the Ohio Agricultural Research and Development Center, the research arm of CFAES. The annual conference offers the latest research and techniques on conservation tillage, which involves leaving the
remains of a harvested crop on a field to reduce erosion, as well as topics including soil quality, managing fertilizer application and precision agriculture.

Farmers planning to spread manure also need to keep watch on the weather, Hall pointed out.

In northwestern Ohio, farmers are barred from applying manure within 24 hours of predicted heavy rainfall, a law that went into effect in 2015 to reduce algal blooms in Lake Erie.

"It could be an unanticipated weather change that causes the problem," Hall said.

A heavy rainfall can carry manure far from the field where it was applied, and Ohio is getting more downpours. There's been a 25 percent increase in intense rainfall events in Ohio since the late 1990s, according to state climate records.

Crops need nitrogen and phosphorous, key ingredients in manure and commercial fertilizers. But when more nutrients are applied to soil than a crop can take up, some can flow with rainwater off the field. Phosphorous can promote the growth of algae in
waterways; algae, when they die and decompose, take up oxygen in the water, reducing what's available for fish and other aquatic life. Also manure contains a lot of ammonia, which binds with oxygen in waterways, leaving less for fish and putting them at risk of
suffocating.

Most of the complaints that the state's regulatory agencies receive about fertilizer application involve residents who report on someone who applied manure, Hall said.

"They see it. They smell it. They don't trust it. And so they call in," Hall said.

Insurance providers for farms that include livestock facilities where manure is collected and spread sometimes refuse to cover any harm, such as a fish kill, that occurs after manure is spread, Hall pointed out.

"They're defining it as pollution," she said.

Then farmers have to foot the entire bill. "It can be costly. That's a concern I have for the farmers," she said.

The price tag hinges in part on the amount and type of fish killed as well as the cost of the investigation into the incident.

Hall's advice to farmers?

"Have a good nutrient management plan, follow that plan, document everything and have good insurance."

If applied correctly, manure can offer rich nutrients to the soil, said Glen Arnold, a manure management specialist with OSU Extension. Arnold will address applying manure to the side of corn plants at the upcoming tillage conference. Arnold helped design
technology that enables farmers to apply manure on a growing crop without crushing the crop.

Since manure is more likely to cause a fish kill than commercial fertilizers, it's important for farmers that do apply manure to incorporate it into the ground immediately or within 24 hours, so it's not left on the surface long, Arnold said.

"Most farmers mean to do well," he said. "We are getting better every year, but there's still room for improvement."

Early registration for the upcoming tillage conference before Feb. 24 costs $65 for one day or $85 for both. Registration after Feb. 24 is $80 a day or $105 for both days. For more information, visit http://ctc.osu.edu.